In a large saucepan, combine water, cauliflower, potatoes, celery, carrots, and onion. Boil for 5 to 10 minutes, or until tender. Set aside.

Melt butter in separate saucepan over medium heat. Stir in flour, and cook for 2 minutes. Remove from heat, and gradually stir in milk. Return to heat, and cook until thickened. Stir in vegetables with cooking liquid, and season with salt and pepper. Stir in cheese until melted, and remove from heat.